Memory cells are electronic devices arranged to store electronic signals. A plurality of memory cells can be combined in various arrangements in order to store a number of bits arranged in bytes, words or other combinations. Various electronic circuits including semiconductor devices such as transistors are used to form memory cells. Memory cells are classified as either volatile (data is lost when power is lost) or non-volatile (data is retained even if power is lost).
Demand for embedded non-volatile memory (“NVM”) in integrated circuits has recently grown significantly. Such memory is used to store serial number information, security information, settings, parameters, computer instructions (firmware) and the like. Desirable characteristics of embedded NVM include low cost, low power consumption, high speed and high reliability (specifically in terms of data retention and program/erase cycling endurance). NVM may be embedded in various integrated circuit (IC) technologies such as, for example, Complementary Metal Oxide Semiconductor (CMOS) technology. NVM is particularly useful in devices comprising computer processors, signal processors, application specific semiconductors (ASICs) and the like. Reprogrammable NVM is particularly important to the emerging field of programmable tags, such as RFID (radio frequency identification) tags which store information inexpensively and can be remotely sensed and/or rewritten without the need to complete an actual circuit with the RFID tag itself.
There is an ever-growing need for NVM with higher storage density, lower power consumption and ease of programming.